(1) Field of the invention
During the study of limonene as a hand cleaner, it was found that fully oxygenated limonene can be made bactericidal and fungicidal as was illustrated by the applicants in U.S. Pat. No. 5,153,229. A review of the literature revealed that oxygenated limonene contains several oxidation products including cis and trans-carveol, trans-p-menth-8-ene-1,2-diol, limonene 1,2-epoxide, limonene 8,9-epoxide, cis and trans-p-mentha-2,8-dien-1-ol, and perillyl alcohol, as was outlined by Blumann in Chemical Abstracts, Volume 63, 1965, on page 1819. Because limonene is not bactericidal and because the chemical structures of limonene and perillyl alcohol are identical except for a hydroxyl group replacing a hydrogen atom at carbon 7, the applicants were surprised to find that perillyl alcohol is bactericidal as was shown in U.S. Pat. No. 5,110,832. A review of the terpenes showed that all the monocyclic monoterpenes that are known to be antimicrobial have an oxygen molecule or hydroxyl group replacing a hydrogen atom at carbons 2, 3, 4, or 8. Prior to the discovery that perillyl alcohol is a bactericide, no monocyclic monoterpene with an oxygen or a hydroxyl group at carbon 7, 9 or 10 was recognized as an antimicrobial compound. After the discovery that perillyl alcohol is a bactericide, the applicants decided to study menth-1-en-9-ol (which has a hydroxyl group at carbon 9) for antimicrobial activity and were pleasantly surprised to find that menth-1-en-9-ol kills bacteria, yeast, and fungi in bactericidal and fungicidal concentrations. The chemical structures of limonene and menth-1-en-9-ol follow below. ##STR1##
Because limonene is not bactericidal and because the chemical structures of limonene and menth-1-en-9-ol are identical except for a hydroxyl group replacing a hydrogen atom at carbon 9, menth-1-en-9-ol was not expected to be bactericidal. It should be noted in the structures of the monocyclic monoterpenes that follow, that none of the monocyclic monoterpenes that are known to be bactericidal, have an oxygen atom or a hydroxyl group at carbon 9 or 10 as can be appreciated in the structures of: perillyl alcohol, carveol, carvone, hydrocarveol, hydrocarvone, pulegone, isopulegol, menthol, menthone, terpinen-4-ol, and a-terpineol which follow. ##STR2##
Because it was not expected, the applicants were surprised to find that menth-1-en-9-ol is bactericidal and fungicidal.
Menth-1-en-9-ol is an oil with a fruity aroma. It is insoluble in water, is poorly soluble in propylene glycol, and is almost insoluble in glycerine. Menth-1-en-9-ol is soluble in alcohol and is miscible in oil. It is a naturally occurring oil, but heretofore, it has not been used as a bactericide and fungicide.
As described by Khanna, Vijay and Ladwa, P. H. in the Indian Journal of Chemistry, Section B 1987, 26B (9), 816-822, menth-1-en-9-ol can be produced by the hydroboration - oxidation of carvone.
(2) Description of the Prior Art
Zuckerman studied the effect of auto-oxidized d-limonene on bacteria, but found it was weakly bacteriostatic, was unstable, and lost its bacteriostatic effect on keeping as was discussed in Nature 168: 517 (1961). He never studied menth-1-en-9-ol. Kurita investigated the fungicidal activity of several components of essential oils as was reported in Biol. Chem.,45(4), 945-952, 1981, but he never studied the bactericidal nor fungicidal activity of menth-1-en-9-ol against bacteria, yeast nor fungi. Murdock and Allen showed that the germicidal effect of sodium benzoate against yeast was enhanced by orange peel oil and d-limonene, as was outlined in Food Technology Vol 14, No 9, 1960, pages 441-5. They never studied the activity of menth-1-en-9-ol against bacteria, yeast nor fungi. Kellner et al demonstrated that ethereal oils and some of the compounds in the oils have anti-bacterial activity as was reported in Arneimittel-Forechung, 5, 224-9, 1955. He confirmed that limonene is not bactericidal. He never studied menth-1-en-9-ol for bactericidal nor fungicidal activity. Gauvreau showed a means of producing disinfecting compositions in U.S. Pat. No. 3,595,975 by combining cetyl pyridinium with terpenes to form antiseptics, but he never studied menth-1-en-9-ol alone nor in combination with cetyl pyridinium hydrochloride. A. Morel revealed the sterilizing action of carveol, dihydrocarveol, and their ozonization products in Comp. Rend. Soc. Biol. Volume 115, pages 536-8 (1934). He demonstrated the bactericidal effect of carveol and dihydrocarveol, but he never studied the bactericidal nor fungicidal activity of menth-1-en-9-ol.
It should be pointed out that drugs which are bactericidal are usually not fungicidal, and drugs which are fungicidal are usually not bactericidal. In addition, drugs which are bactericidal frequently promote the growth of yeast. Table A, which follows, exemplifies the bactericidal and fungicidal activity of several commonly used antibacterial, antiyeast, and antifungal antibiotics.
TABLE A ______________________________________ ANTIBIOTIC ACTIVITY AGAINST Gm.sup.+ Gm.sup.- ANTIBIOTICS Bac Bac AFBact Yeast Fungi ______________________________________ A. ANTIBACTERIAL 1. Ampicillin YES YES NO NO NO 2. Cephlothin YES YES NO NO NO 3. Chloram- YES YES NO NO NO phenicol 4. Erythromycin YES NO NO NO NO 5. Ethambutol NO NO YES NO NO 6. Gentamicin YES YES NO NO NO 7. Isoniazid NO NO YES NO NO 8. Nitro- NO YES NO NO NO furantoin 9. Penicillin YES NO NO NO NO 10. Rifampin YES NO YES NO NO 11. Streptomycin YES YES YES NO NO 12. Sulfonamides NO YES NO NO NO 13. Tetracycline YES YES NO NO NO 14. Vancomycin YES YES NO NO NO B. ANTIYEAST 1. Nystatin NO NO NO YES NO 2. Gentian NO NO NO YES NO violet C. ANTIFUNGAL 1. Chlotri- NO NO NO YES YES mazole 2. Griseofulvin NO NO NO NO YES ______________________________________ Gm.sup.+ Bac = Gram Positive Bacteria, Gm.sup.- Bac = Gram Negative Bacteria, AFBac = Acid Fast Bacteria, YES = Kills Organism, NO = No Activity Against Organism
It should be noted from the table above that none of the anti-bacterial antibiotics kill yeast nor fungi, and none of the anti-yeast nor anti-fungal antibiotics kill bacteria. Thus, an anti-fungal or anti-yeast antibiotic is not expected to kill bacteria and an anti-bacterial antibiotic is not expected to kill yeast nor fungi. Anti-fungal antibiotics do not necessarily kill yeast and anti-yeast antibiotics do not necessarily kill fungi.